{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-46116", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-46116", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-05-28T09:35:30.689Z", "updatedAt": "2026-10-19T19:26:44.530Z", "importedAt": "2026-10-24T01:58:14.884Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "xfrm: defensively unhash xfrm_state lists in __xfrm_state_delete", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: defensively unhash xfrm_state lists in __xfrm_state_delete\n\nKASAN reproduces a slab-use-after-free in __xfrm_state_delete()'s\nhlist_del_rcu calls under syzkaller load on linux-6.12.y stable\n(reproduced on 6.12.47, also reachable via the same code path on\ntorvalds/master and on the ipsec tree). Nine unique signatures cluster\nin the xfrm_state lifecycle, the load-bearing one being:\n\n BUG: KASAN: slab-use-after-free in __hlist_del include/linux/list.h:990 [inline]\n BUG: KASAN: slab-use-after-free in hlist_del_rcu include/linux/rculist.h:516 [inline]\n BUG: KASAN: slab-use-after-free in __xfrm_state_delete net/xfrm/xfrm_state.c\n Write of size 8 at addr ffff8881198bcb70 by task kworker/u8:9/435\n\n Workqueue: netns cleanup_net\n Call Trace:\n __hlist_del / hlist_del_rcu\n __xfrm_state_delete\n xfrm_state_delete\n xfrm_state_flush\n xfrm_state_fini\n ops_exit_list\n cleanup_net\n\nThe other observed signatures hit the same slab object from\n__xfrm_state_lookup, xfrm_alloc_spi, __xfrm_state_insert and an OOB\nwrite variant of __xfrm_state_delete, all on the byseq/byspi\nhash chains.\n\n__xfrm_state_delete() guards its byseq and byspi unhashes with\nvalue-based predicates:\n\n\tif (x->km.seq)\n\t\thlist_del_rcu(&x->byseq);\n\tif (x->id.spi)\n\t\thlist_del_rcu(&x->byspi);\n\nwhile everywhere else in the file (e.g. state_cache, state_cache_input)\nthe safer hlist_unhashed() check is used. xfrm_alloc_spi() sets\nx->id.spi = newspi inside xfrm_state_lock and then immediately inserts\ninto byspi, but a path that observes x->id.spi != 0 outside of\nxfrm_state_lock can still skip-or-hit the byspi unhash inconsistently\nwith whether x is actually on the list. The same holds for x->km.seq\nversus byseq, and the bydst/bysrc unhashes have no predicate at all,\nso a second __xfrm_state_delete() on the same object writes through\nLIST_POISON pprev.\n\nThe defensive change here:\n\n - Use hlist_del_init_rcu() instead of hlist_del_rcu() on bydst,\n bysrc, byseq and byspi so a second deletion is a no-op rather\n than a write through LIST_POISON pprev. The byseq/byspi nodes\n are already initialised in xfrm_state_alloc().\n - Test hlist_unhashed() rather than the value predicate for\n byseq/byspi, so the unhash decision tracks list state rather than\n mutable scalar fields.\n\nEmpirical verification: applied this patch on top of v6.12.47, rebuilt,\nand re-ran the same syzkaller harness for 1h16m on a previously-crashy\nconfiguration that produced ~100 hits each of slab-use-after-free\nRead in xfrm_alloc_spi / Read in __xfrm_state_lookup / Write in\n__xfrm_state_delete. After the patch, 7.1M execs across 32 VMs at\n~1550 exec/sec produced zero xfrm_state UAF/OOB hits. /proc/slabinfo\nconfirms the xfrm_state slab is actively allocated and freed during\nthe run (~143 KiB resident), so the fuzzer is still exercising those\ncode paths -- they just no longer crash.\n\nReproduction:\n\n - Linux 6.12.47 x86_64 + KASAN_GENERIC + KASAN_INLINE + KCOV\n - syzkaller @ 746545b8b1e4c3a128db8652b340d3df90ce61db\n - 32 QEMU/KVM VMs x 2 vCPU on AWS c5.metal bare metal\n - 9 unique signatures collected in ~9h, all within xfrm_state\n lifecycle", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "7b4dc3600e4877178ba94c7fbf7e520421378aa6", "status": "affected", "versionType": "git", "lessThan": "6b4dc3181b4bfc5f5fc33ab33b1dc6e15759f4b6" }, { "version": "7b4dc3600e4877178ba94c7fbf7e520421378aa6", "status": "affected", "versionType": "git", "lessThan": "3943fcad7694a7d0b15aeabe7d3cc2a2eb8e92e8" }, { "version": "7b4dc3600e4877178ba94c7fbf7e520421378aa6", "status": "affected", "versionType": "git", "lessThan": "2c617848ae6e4f07a3e397f604208c293bbecacc" }, { "version": "7b4dc3600e4877178ba94c7fbf7e520421378aa6", "status": "affected", "versionType": "git", "lessThan": "b4a53add2fa8f1b5aa17d4c5686c320785fab182" }, { "version": "7b4dc3600e4877178ba94c7fbf7e520421378aa6", "status": "affected", "versionType": "git", "lessThan": "26edb0a3c99f9d958c212be68b21f1221614dcf0" }, { "version": "7b4dc3600e4877178ba94c7fbf7e520421378aa6", "status": "affected", "versionType": "git", "lessThan": "4980162de555cb838f1a189ce7d2cbf5d2e7b050" }, { "version": "7b4dc3600e4877178ba94c7fbf7e520421378aa6", "status": "affected", "versionType": "git", "lessThan": "a2e2d08fb070fab4947447171f1c4e3ca5a188e5" }, { "version": "7b4dc3600e4877178ba94c7fbf7e520421378aa6", "status": "affected", "versionType": "git", "lessThan": "14acf9652e5690de3c7486c6db5fb8dafd0a32a3" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "2.6.19", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "2.6.19" }, { "version": "5.10.261", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.210", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.176", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.140", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.88", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.30", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.0.7", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.0.*" }, { "version": "7.1", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }